I don't know. But if i had to choose between the two, i would choose Softmaker office. It is a well known and established office suite. The company also dedicates itself on building and providing office products. Ashampoo is kinda Jack of all trade on the other side.
I have seen to mention, that Ashampoo is based on Softmaker. 5 licences for $20, that is a really good price.
But you should trial it before buying. All office suites claim to be compatible with MO, but many fail to deliver.
As far as I know, there is none. I would go for Ashampoo for the discounted price. I once purchased the 2012 version and it was good for basic needs! I only use MS Office and is some cases Mobisystems OfficeSuite Premium which is very good by the way.
Now Softmaker offers to models. One is a one-time payment and you get updates until another major version is released. The other is a subscription; you get free updates as long as your subscription is valid. Ashampoo only offers the standard edition. Please note that both Ashampoo and Softmaker editions will get the same service packs updates.